Ergonomic Side Chair

ABSTRACT

A reclinable chair is disclosed having right and left side connectors for pivotally connecting a backrest to a base assembly. The connectors bias the backrest into the upright position when unoccupied. In certain embodiments, the connectors can comprise elastic members, ball joints, or a plurality of elastic springs.

This application is a continuation of U.S. application Ser. No.11/277,450 filed on Mar. 24, 2006, which is hereby incorporated byreference in its entirety.

BACKGROUND

The application of scientific information to the design of objects,systems and environments for human use has resulted in a revolution inthe seating industry. Typically, the cost of applying the scientificinformation was economical in only the more expensive types of seating(e.g., executive office chairs). The more affordable side chairs,temporary chairs, and stackable chairs were designed more foraffordability and ease of storage than for the comfort of the user.

These design priorities led to the design of uncomfortable chairs. Forexample, chairs are manufactured with large apertures in the center ofthe seat to accommodate stacking. U.S. Pat. No. 2,967,565 to Schultzdiscloses a stackable chair with a large aperture in the center of theseat to allow a number of the chairs to be stacked by sliding the seat'spedestal into the large aperture. The '565 patent also discloses usingrigid seats that resist the bending or torsional strains accompanyingits ordinary use. The large aperture and the rigid seat make the chairuncomfortable. Other seats failed to provide proper lumbar support. U.S.Pat. No. 5,123,702 to Caruso discloses a stacking chair with an integralseat and backrest in a substantial “L” shape. When a user reclines, thebackrest and seat flatten out causing the user to slide forward on theseat. Further, because the backrest pivots at the base connection withthe seat, the user's lumbar is not supported. Another, U.S. Pat. No.5,868,468 to Wang, discloses a chair having an adjustable inclination.The '468 patent discloses a backrest that pivots at a point below theseat and, therefore, cannot provide proper lumbar support for the user.

As more is learned about the operation of the human body and throughtechnological advances, the design priorities for more affordable,temporary, and stackable chairs now include user comfort. The presentinvention solves all of the problems associated with the related art byproviding an ergonomic chair in which the comfort of the user is adesign priority.

SUMMARY OF THE INVENTION

An embodiment of the chair comprises a support means and a seat attachedto the support means. Preferably the seat is a one-piece shell and hastab-forming slots in a pressure-reducing pattern at predeterminedpressure point locations. The predetermined pressure point locations maybe in the zones of the user's ischial protuberosities (i.e., sittingbones) when the user is properly seated and the pressure-reducingpattern can be an H-pattern, an elongated H-pattern, or any othertab-forming pattern.

In another aspect of the invention, the chair comprises a left sidefront leg, a right side front leg, a left side rear leg attached to theseat, a right side rear leg attached to the seat, and a front crossbarattached between the front legs. Preferably, the front of the seat isattached to a mesial point of the front crossbar. In a preferredembodiment, the seat has at least one slot in the front of the seat fordefining two flexing seat extensions. The two flexing seat extensionspreferably are able to move in relation to one another. In analternative embodiment, the slot in the front of the seat is “V” shaped.A further aspect of the invention may also comprise a left side lumbarmount extending above the seat and attached to the left rear leg, aright side lumbar mount extending above the seat and attached to theright rear leg, a lumbar support means attached to the left side lumbarmount and the right side lumbar mount, and a backrest attached to thelumbar support means. Preferably, the lumbar support means comprises aband of elastic material (e.g., elastomer, textile, or the like), butalternatively it may comprise a pair of connectors (e.g., flap ofelastic material or a ball joint). Specifically, the alternativeembodiment comprises a left side connector attached to the left sidelumbar mount and pivotally attached to the left side of the backrest anda right side connector attached to the right side lumbar mount andpivotally attached to the right side of the backrest. In another aspect,the chair backrest may have one or more vertical slots extending downfrom the top of the backrest. The vertical slots operate to define twoor more flexing backrest extensions, which can move in relation to oneanother. Instead of a plurality of vertical slots in the backrest, thebackrest may have a single vertical slot extending down from the stop ofthe backrest. The single vertical slot would define two flexing backrestextensions, which can move in relation to one another. This embodimentmay also include an expanded vertical slot chair grip adapted toaccommodate a user's hand.

An alternative embodiment of the chair comprises a support means, a seatattached to the support means, a left side lumbar mount extending abovethe seat and attached to the support means, a right side lumbar mountextending above the seat and attached to the support means, a lumbarsupport means attached to the left side lumbar mount and the right sidelumbar mount, and a backrest attached to the lumbar support means. Thelumbar support means may comprise a left side connector attached to theleft side lumbar mount and pivotally attached to the left side of thebackrest and a right side connector attached to the right side lumbarmount and pivotally attached to the right side of the backrest.Alternatively, the lumbar support means may be a band of elasticmaterial or the like. The embodiment may also comprise one or morevertical slots extending down from the top of the backrest. Preferably,the one or more vertical slots define two or more flexing backrestextensions, which are able to move in relation to one another. Insteadof a plurality of vertical slots in the backrest, the backrest may havea single vertical slot extending down from the top of the backrest. Thesingle vertical slot would define two flexing backrest extensions, whichcan move in relation to one another. This embodiment may also include anexpanded vertical slot chair grip adapted to accommodate a user's handand can be used as a handle to pick up the chair. In another embodimentof the invention, the support means comprises a left side front leg, aright side front leg, a left side rear leg attached to the seat, a rightside rear leg attached to the seat, and a front crossbar attached to thefront legs and the seat. Preferably, the seat is attached to a mesialpoint of the front crossbar and has at least one slot in the front ofthe seat for defining two flexing seat extensions, which are able tomove in relation to one another. In an alternative embodiment the slotin the front of the seat is “V” shaped.

In another aspect of this embodiment of the invention, the seatcomprises tab-forming slots in a pressure-reducing pattern atpredetermined pressure point locations. It is preferred that thepredetermined pressure point locations are in the zones of the user'sischial protuberosities when the user is properly seated. It is alsopreferred that the pressure-reducing pattern is an H-pattern or anelongated H-pattern.

An alternative embodiment of the invention comprises a support means, aseat attached to the support means, and a backrest having a lumbarregion and a flex region. Preferably, the lumbar region is flexible andattached to the support means and the flex region is more flexible thanthe lumbar region. In one embodiment, the lumbar region and flex regionmay be constructed of the same material and the lumbar region has athicker layer of material than the flex region to make it less flexible.In a further embodiment, the lumbar region and flex region areconstructed of the same material and the lumbar region is reinforced tomake is less flexible. In an even further embodiment, the lumbar regionand flex region are constructed of substantially different materials andthe lumbar region is a less flexible material than the flex regionmaterial.

The present invention may also be constructed with an integral seat andbackrest. In this embodiment, the invention comprises a support meansand an integral shell having a seat portion and a backrest portion insubstantially an L-shape. Preferably, the seat portion is attached tothe support means. It is also preferred that the backrest portion has alumbar region and a flex region where the flex region is more flexiblethan the lumbar region.

Another aspect of the present invention comprises a spring connected toone or more of the bottoms of the chair legs. In a preferred embodiment,the chair comprises a support means having three or more legs, each ofthe legs having a top and a bottom, a spring attached the bottom of oneor more of the legs, and a seat attached to the support means.

It is an even further aspect of the present invention to have thesupport means adapted to be telescopically received on additionalidentical chairs to form a space-saving stack of chairs.

A further alternative embodiment of a stackable chair comprises three ormore legs having a top and a bottom, springs attached t the bottom ofone or more legs, a seat attached to the top of the legs at two pointson either side of the rear of the seat and at the approximate centerpoints of the front of the seat, two lumbar mounts attached to one ormore of the legs and extending above the seat, a lumbar support attachedbetween the two lumbar mounts, and a backrest attached to the lumbarsupport. Preferably, the seat has at least two slots in an elongatedH-pattern at predetermined pressure point locations and at least oneslot in the front of the seat to allow flexing of the seat.

An even further alternative embodiment of a stackable chair comprises aleft side front leg, a right side front leg, a left side rear leg, aright side rear leg, a front crossbar attached at a proximal end to onefront leg and at a distal end to the other front leg, a seat having tabforming slots in an elongated H-pattern in the zones of the user'sischial protuberosities when the user is properly seated, a left sidelumbar mount extending above the seat and attached to the left rear leg,a right side lumbar mount extending above the seat and attached to theright rear leg, a band of elastic material attached to the left sidelumbar mount and the right side lumbar mount, and a backrest attached tothe lumbar support means, a vertical slot extending down from the top ofthe backrest, defining two flexing backrest extensions, which are ableto move in relation to one another. In a preferred embodiment, the frontof the seat is attached to a mesial point of the front crossbar and therear of the seat is attached to the rear legs. It is also preferred thatthe seat has at least one slot extending from the front of the seattowards the rear of the seat defining two flexing seat extensions, whichare able to move in relation to one another.

BRIEF DESCRIPTION OF THE DRAWINGS

For purposes of illustrating the invention, there is shown in thedrawings forms, which are presently preferred. It is understood,however, that the invention is not limited to the precise arrangementand instrumentalities shown.

FIG. 1 is an illustration showing a front perspective view of oneembodiment of the ergonomic chair.

FIG. 2 is an illustration showing the bottom view of one embodiment ofthe ergonomic chair.

FIG. 3 is an illustration showing the rear perspective view of oneembodiment of the ergonomic chair.

FIG. 4 is an illustration showing a rear perspective view of analternative embodiment of the ergonomic chair.

FIG. 5 is an illustration showing a rear perspective view of analternative embodiment of the ergonomic chair.

FIG. 6 is an illustration showing a rear perspective view of analternative embodiment of the ergonomic chair.

FIG. 7 is an illustration showing a partial rear perspective view of analternative embodiment of the ergonomic chair.

FIG. 8 is an illustration showing a spring mechanism and a leg of theergonomic chair.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. The invention may, however, be embodied inmany different forms and should no be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to the like elements.

The present invention is a chair, which provides improved comfort whilemaintaining simplicity in its design. The stackable chair embodiment ofthe invention is particularly useful when the chairs are for temporaryuse.

Referring to FIGS. 1 through 8, embodiments of the invention shall bedescribed in detail. Initially, with reference to FIGS. 1-3, a chairhaving legs, 1, 2, 3, 4 and a seat 6 is shown. Right crossbar 14connects legs 1, 2 and left cross bar 12 connects legs 3, 4. Rearcrossbar 10 is connected on one end to the rear portion of right crossbar 14 and on the other end to the rear portion of left crossbar 12.Front crossbar 8 is connected on one end to a front portion of rightcrossbar 14 and on the other end to front portion of left crossbar 12.Preferably, the legs 1, 2, 3, 4 and crossbars 8, 10, 12, 14 are tubularpoles. The cross-section of the legs and crossbars, however, can be avariety of solid or hollow shapes. The legs are substantially verticaland the crossbars are substantially horizontal. It is also preferredthat the connection points are welded joints. These connection pointsmay be accomplished by other means such as mechanical fasteners, glues,or the like. Crossbars 8, 10, 12, 14 and legs 1, 2, 3, 4 provide asubstantially rectangular frame support means for seat 6. The crossbars8, 10, 12, 14 are all optional in certain embodiments of the design andmay be eliminated by attaching the respective legs to the seat 6. Thesupport means in some embodiments may be three or more legs, a singlepedestal, a wall mount, a transverse bar mount, or the like. The onlyembodiment for which the front crossbar 8 is required is when the seat 6is attached to a mesial point on the front crossbar 8. In this preferredembodiment, seat 6 is attached to a mesial point of front crossbar 8 byfastener 16. The rear of the seat 6 can be attached directly to rearlegs 1, 4 or, preferably, to rear crossbar 10 by fasteners 18, 20. Thefasteners 16, 18, 20 can be any type of fasteners including mechanicalfasteners, such as screws, grommets, or the like and other fasteningmeans known in the art. Seat 6 is preferably made of flexible plasticand is molded into a dish shape having a downward sloping front portionand an upward sloping rear portion. The flexible plastic seat ma beinjection molded plastic such as TPR or some other material known in theindustry. In a preferred embodiment, leg 3 and left crossbar 12 are asingle integral piece shaped substantially into an “L” configuration.Similarly, in a preferred embodiment, the minor image leg 2 and rightcrossbar 14 are a single integral piece shaped substantially into an “L”configuration. In an alternative embodiment, the left crossbar 12 andright crossbar 14 are optional and the left front leg 3 and right frontleg 4 can be attached directly to the seat or attached to front crossbar8, which is attached to the seat 6. It is also preferred that rear legs1, 4 extend above the connection point with crossbars 12, 14 and abovethe seat 6 to form lumbar mounts 24, 26. Alternatively, the lumbarmounts 24, 26 may be separate members attached to the rear legs 1, 4,the rear crossbar 10, or the seat 6. In an alternative embodiment,armrests, which are well known in the art, may be attached to the lumbarmounts 24, 26 or any other part of the chair.

The lumbar mounts 24, 26 create the support points for the backrest 22.Referring now to FIG. 3, lumbar support 32 is attached to lumbar mount24 and lumbar mount 26. The lumbar support 32 may be attached to thelumbar mounts 24, 26 by any means known in the industry. Preferably,lumbar support 32 is attached to lumbar mounts 24, 26 by forming sleevesat the ends 28, 30 of lumbar support 32 and inserting lumbar mounts 24,26 into sleeves 28, 30. The sleeves 28, 30 surrounding the lumbar mounts24, 26 can be slid up and down the lumbar mounts 24, 26 to adjust theheight of the backrest 22 or they can be fixed in place. Lumbar support32 is preferably made of an elastic material and exerts a bias on thebackrest 22 to place it in an upright or un-reclined position when notoccupied. Backrest 22 is attached to lumbar support 32 by mechanicalfasteners, glues, or the like. Backrest 22 is preferably made offlexible plastic and is molded into an ergonomic shape, which providessupport to the user's lumbar region (i.e., the area between the thoracicvertebrae and sacrum). The flexible plastic seat may be injection moldedplastic such as TPR or some other material known in the industry.

In operation, an occupant can recline by applying a rearward pressure onthe upper portion of the backrest 22. When the user applies pressure, itacts as a torque force on the lumbar support 32. The lumbar support 32will twist and allow the backrest to recline. Because the pivot pointfor the backrest is the lumbar region of the occupant, the bottom of thebackrest 22 will move forward as the top of the backrest moves rearwardand the chair will continue to support the occupant's lumbar region evenin a fully reclined state.

In the alternative embodiments shown in FIGS. 4-7, the backrest isattached to the lumbar mounts 24, 26 using separate pieces of elasticmaterial or other well known mechanical means (e.g., a ball joint) forpivotally connecting the lumbar mounts to the lumbar region of thebackrest 22. In this embodiment, lumbar support 32 is not used. Themeans for connected the lumbar mounts 24, 26 to the backrest preferablyexert a bias on the backrest 22 to place it in the upright orun-reclined position when not occupied. Specifically, with reference toFIG. 4, a connector comprising a sleeve 25, 27, which is attached tolumbar mounts 24, 26, respectively, and an elastic flap 29, 31 attachedto the sleeve 25, 27 and the backrest 22 operate as a pivotalconnection.

In operation, an occupant can recline by applying a rearward pressure onthe upper portion of the backrest 22. When the user applies pressure, itacts as a torque force on the means for connecting the lumbar mounts(i.e., elastic flat 29, 31). The means for connecting the lumbar mountswill twist and allow the backrest to recline. Because the pivot pointfor the backrest is the lumbar region of the occupant, the top portionof the backrest 22 will move in a rearward direction and the portion ofthe backrest below the pivot point will move in a forward direction. Thepivoting of the backrest 22 will result in the backrest 22 supportingthe occupant's lumbar region even in a fully reclined state.

Referring to FIG. 5, an alternative embodiment is shown in which thebackrest connectors comprise a sleeve 35, 37 attached to lumbar mounts24, 26, respectively, and backrest mount 43, 45 connected to thebackrest 22. A plurality of elastic strips 39, 41 or springs areconnected between the sleeve 35, 37 and the backrest mount 43, 45respectively. The backrest mount 43, 45 is preferably a rectangularmember the length of the lumbar region and is adapted to be attached tothe backrest 22 and to receive a plurality of elastic strips 39, 41 orsprings. The operation is similar to the operation of the embodiment inFIG. 4. Alternatively, this embodiment may have a single backrest mountas shown in FIG. 6. Specifically, the plurality of elastic strips 39, 41or springs are connected between the sleeve 35, 37 and backrest mount47.

In another alternative embodiment illustrated in FIG. 7, a ball joint isused to pivotally attach the backrest 22 and lumbar mounts 24, 26. Anenlarged drawing of the ball joint is shown in FIG. 7. It should beunderstood that the side not shown is a mirror image of the side shown.Specifically, a first ball joint mount 49 is attached to lumbar mount24. Preferably, the first ball joint mount 49 has an integral sleevethat slides over lumbar mount 24. A first ball bearing 53 is rotatablyattached to first ball joint mount 49. A first ball joint member 51 isfixedly attached to backrest 22 and rotatably attached to the first ballbearing 53. The ball joint structure is for illustrative purposes onlyand it should be understood that any mechanical linkage means forpivotally connecting the backrest to the lumbar mounts can be used. In apreferred embodiment, the ball joint includes a spring bias to place thebackrest in an upright or un-reclined position when not occupied.

Another alternative embodiment comprises a backrest with a flex regionlocated in the upper portion of the backrest and a lumbar region in thelower portion of the backrest. The flex region is more flexible than thelumbar region. The difference in flexibility of the regions can beaccomplished in several ways. Specifically, the difference inflexibility may be achieved by making (1) the flex region and the lumbarregion from the same material, but the flex region is made more flexibleby it being a thinner layer of material than the lumbar region; (2) theflex region and the lumbar region could be made from the same material,but the lumbar region is made less flexible by reinforcing it withanother material (e.g., metal) or additional structure (e.g., spines,struts, or trusses); or (3) the lumbar region is made from a lessflexible material than the flex region. However the backrest is madeinto two regions of differing flexibility, it is then attached to thelumbar mounts either directly or in a manner described in one of theother embodiments.

In operation, an occupant can recline by applying a rearward pressure onthe flex region (upper portion) of the backrest 22. The flex region willdeflect in a rearward direction and at the same time the lumbar regionwill deflect in a rearward direction-albeit less than the flex regionbecause of the regions relative flexibilities. Because the pivot pointfor the backrest is the lumbar region of the occupant, the chair willcontinue to support the occupant's lumbar region even in a fullyreclined state.

The ability to recline the backrest 22 and maintain lumbar supportvastly increases the comfort of the chair. The user's comfort is furtherincreased by re-distribution of an occupant's weight over a greater areaof the chair to reduce pressure points on the occupant's body. Thisre-distribution or equalization of pressures is accomplished bydesigning the seat and backrest to flex at the places where highpressure points typically occur.

The seat 6 and backrest 22 are made more flexible by the inclusion ofone or more types of pressure-reducing slots. A slot is a cut, which iscompletely through the material. A pressure-reducing slot is located onthe front of the seat near its center. The front seat slot 34 extendsfrom the front of the seat approximately four inches towards the rear ofthe seat to form front seat extensions 36, 38. It should be understoodthat the slot may be longer or shorter than 4 inches and the specificmeasurement was provided for illustrative purposes only. The front seatextension 36, 38 are able to deflect downward independently from oneanother when a user exerts a downward force with his legs. This ispossible because the front of the seat 6 is connected at a single mesialpoint of front crossbar 8 by fastener 16 and the front seat extension36, 38 extend beyond the front crossbar 8. Thereby, allowing theunattached front seat extensions 36, 38 to move. In operation, theoccupant's legs will be supported by the front seat extensions 36, 38,but will deflect downward or twist when the pressure on the occupant'slegs exceeds the amount of pressure needed to flex the front seatextensions 36, 38. The seat, therefore, can be constructed to flex at apoint before the pressure on the occupant's leg becomes uncomfortable.

The seat also has pressure-reducing slots in the zones of the user'sischial protuberosities, or commonly referred to as the user's sittingbones. It is these sitting bones that receive the highest amount ofpressure when seated. As depicted in FIGS. 1 & 2, the zones of theuser's ischial protuberosities, when a user is properly seated, aretypically located on the rear of the seat 6. As shown in FIG. 2, theslots for the sitting bones are formed, preferably, in an elongated “H”pattern in the seat 6. The elongated “H” pattern slots 40, 42 are minorimages of one another in FIG. 2. Seat 6 may also have an “H” patternslot instead of an elongated “H” pattern slot. The elongated “H” patternslots and the “H” pattern slots form tables in the seat. The elongated“H” pattern slot 40, 42, preferably, comprises a single line in onedirection and two lines substantially perpendicular to and intersectingthe single line. The single line can be from substantially front to backof the seat or substantially side-to-side of the seat. One of thedifferences between the elongated “H” pattern is the single line of theelongated “H” pattern extends beyond the intersection point with the twoperpendicular lines and the single line of the “H” pattern terminates atthe intersecting point with perpendicular lines. Further, the elongated“H” pattern has slots that form substantially rectangular tabs that aredisconnected from the seat on two sides (two-sided tabs 104, 106, 108,110) or three sides (three sided tabs 100, 102). The three-sided tabs100, 102 will flex under less pressure than the two-sided tabs 104, 106,108, 110. The “H” pattern will have only three-sided tabs 100,102. It isto be understood that any slot pattern that forms flexible tabs may beused.

The chair may also have a pressure-reducing slot in the backrest. Thebackrest slot 44 extends from the top of the backrest 22 towards thebottom of the backrest. The backrest slot 44 allows the backrest's upperhalves 46, 48 to flex independently of one another. For example, as theuser turns right, his right shoulder exerts a rearward force on backrestextension 46 causing it to flex in the rearward direction while backrestextension 48 remains in place and continues to support the left side ofthe occupant's back. Preferably, the backrest slot 44 is approximatelyeight inches long. Although, the backrest slot 44 may be longer orshorter than eight inches depending on the desired flexibility.Optionally, the backrest slot 44 forms a chair grip at its midpoint bywidening to approximately five inches for approximately two inches andthen narrowing again to the width of the slot. The five-inch by two-inchrectangular cutout or chair grip is large enough to accommodate a humanhand and acts as a handle for carrying and lifting the chair.

Another aspect of the invention is one that is often ignored whendesigning non-cushioned chairs. As a user moves from a standing positionto a sitting position, the body will develop some momentum to continuedownward when the user's body comes in contact with the seat. Oncushioned chairs, the momentum force is dissipated by slowlydecelerating the user by compressing the cushion. A non-cushioned chair,however, cannot slowly decelerate the user and as a result, the userwill impact the seat. This impact may cause the user discomfort or inextreme cases may cause injury to the user. The embodiment illustratedin FIG. 8 uses a spring mechanism to reduce the impact on the user.Essentially, the spring mechanism acts to slowly decelerate the user bycompressing a spring just as a cushioned seat decelerates a user bycompressing the cushion. One or more of the legs may have springmechanisms interposed between legs and the floor. Specifically, thespring mechanism comprises a foot 50 attached to a rod 56. The rod 56 ispartially contained in a cavity of the chair's leg and partially outsidethe leg cavity. FIG. 8 shows the spring mechanism removed from the legcavity for the purposes of showing the structure of the springmechanism. In operation, the entire spring mechanism above cap 54 iscontained in the leg cavity. The cap 54 fits adjacent to the bottom ofthe leg. The cap 54 has an opening through which the rod 56 may slide. Aspring surrounds the rod 56 between the foot 50 and the cap 54.Preferably, spacers 58, 60 assist the rod in sliding smoothly within theleg cavity. Screw 62 secures the spring mechanism to the leg throughscrew-hole 63. Preferably, the spring mechanism is attached to the rearlegs 1, 4.

In operation, when the seat is unoccupied, spring 52 is fully extendedand the minimum amount of rod 56 is contained in the leg cavity. Thechair will be elevated in this unoccupied state. When the seat isoccupied, the weight of the occupant will cause the spring 52 tocompress and will drive the rod 56 further up into the leg cavity. Theseat will move in a downward direction until the downward force exertedby the occupant's weight equals the upward force exerted by the spring.

The operation of the preferred embodiment of the ergonomic chair willnow be described. A user sitting down would initially feel the seat movedownward as the rear leg springs 50, 52 compressed. This downwardmovement relieves a portion of the initial impact pressure on theoccupant from the act of sitting down. As the occupant settles into theseat, the three-sided tabs 100, 102 would flex in a downward directionand two-sided tabs 104, 106, 108, 110 would flex in a downward directionto a lesser degree than three-sided tabs 100, 102. The flexing of thesetabs causes the occupant's weight to be supported to a greater degree bysections of the seat outside of the occupant's ischial protuberositieszones. This redistribution results in an equalization of forces on theoccupant, which increases the occupant's comfort. A further equalizationof pressure on the occupant results from the front seat slot, whichallows the front seat extensions 36, 38 of the seat 6 to move in adownward direction. As the front seat extensions 36, 38 flex downward,other sections of the seat begin to support the occupant to a greaterextent until the forces on the occupant are sufficiently redistributedso that the front seat extensions 36, 38 do not deflect any further.

As would be readily envisioned by one of skill in the art, the variousmechanisms described herein are particularly useful in combination forproviding functional, attractive support mechanisms that allow for easyposition adjustment of attached devices. All combinations of themultiple mechanisms described herein are therefore encompassed by thepresent invention.

Preferentially, unless otherwise indicated the various components of thepresent invention are constructed generally out of a strong, lightweightmaterial, such as aluminum. Various different materials could also beused, such as other metals or plastics.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teaching presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

1. A chair comprising: a) a base; b) a seat supported by the base; c) aright side lumbar mount attached to the base, the right side lumbarmount extending above the seat; d) a left side lumbar mount attached tothe base, the left side lumbar mount extending above the seat; e) abackrest; f) a right side connector attaching the backrest to the rightside lumbar mount; and g) a left side connector attaching the backrestto the left side lumbar mount.
 2. The chair of claim 1, wherein theright side connector and the left side connector are each elasticmembers, the elastic members biasing the backrest into an uprightposition.
 3. The chair of claim 1, wherein the right side connector andthe left side connector are each ball joints, the ball joints eachcomprising a ball bearing disposed within a ball joint housing.
 4. Thechair of claim 3, wherein the right and left side ball joints eachcomprise a spring biasing the backrest into an upright position.
 5. Thechair of claim 1, wherein the right side connector and the left sideconnector each comprise a plurality of elastic springs.
 6. The chair ofclaim 5, wherein the elastic springs are attached to the backrest at oneattachment point in the center of the backrest.